Power transmission



June 19, 1951 W. M. SIESEL POWER TRANSMISSION 7- Shee'bS-SheBt 1 Filed Oct. 19, 1945 IN V EN TOR. William diesel June 1 9, 1951 w. M. SIESEL POWER mmsuxsszon 7 Sheets-Sheet 2 Filed Oct. 19, 1945 INVENTOR. Mam/1mm flay-U, 5%;

June 19, 1951 w. M. SIESEL 2,557,894

, POWER TRANSMISSION Filed Oct. 19, 1945 7 Sheets-Sheet 3 IN VEN TOR.

BY Jiesel ATTORNEYS June 19, 1951 w. M. SIVESEL 2,557,894

POWER musurssxou Filed Oct. 19, 1945 7 Sheets-Sheet 4 INVENTOR.

i BY IWli'am/Y J7me! w. M. SIESEL POWER TRANSMISSION June 19, 1951 7 Sheets- Sheet 5 Filed Oct. 19, 1945 r IN V EN TOR.

diesel v TOR/V575 June, 19, 1951 w. M. SIESEL POWER TRANSMISSION 7 Sheets-Sheet 6 Filed Oct. 19, 1945 i/vaa 13/ INVENTOR. mam! W! I BY June 19, 1951 w. M. SIESEL POWER msmssron 7 Sheets-Sheet 7 Filed Oct. 19, 1945 I N V EN TOR. BY mifiam/Y J1me! 1/ TOR/I576 Patented June 19, 1951 POWER TRANSMISSION William M. Siesel, Morrlsville, Pa., assignor to Continental, Incorporated, Washington, D. C., a corporation of Connecticut Application October 19, 1945, Serial No. 623,339

4 Claims. (Cl. 74-645) This invention relates to a power unit for drlv ing a vehicle. More particularly the invention relates to such a unit adapted for use in a dual purpose vehicle, e. g., one powered by an airplane engine, or designed to serve both as a land vehicle and as an aircraft.

Upon the development of reliable, light, lowcost airplanes it was generally assumed that a large market would develop, just as two decades earlier the automobile market had developed. Such expectations have not been realized; and upon analysis it is evident that one of the principal objections which has held them back is the fact that airplanes can take a person only from an airport to another airport.

Airports are of necessity located on the outskirts of communities, not infrequently many miles from the fliers home. Thus the time saved by the speed of aerial travel is often consumed in waiting for transportation to and from the airports.

Furthermore the expense of transportation between the airport and the actual destination is often such as to make the economy of actual aerial travel seem a fallacy. Even if a flier drives his own automobile to the airport of departure, when he lands at the airport of destination, he is still dependent upon taxis or buses. When the expense for taxis and buses and the expense of the automobile are added to the expenses of ownership, upkeep and operation of the plane, and the initial cost of the plane is taken into consideration, it is easy to see why few persons consider it feasible to own both an automobile and an airplane.

Since the average man makes at least a hundred'trips of five miles or less in his automobile to every trip which is long enough to use an airplane between airports, and since he cannot afford both an automobile and an airplane, his choice between them is obvious.

It has often been suggested that the ideal vehicle would be one which could fly like an airplane and then, upon landing, could remove or fold its wings, propeller, etc., and drive down the roads like an automobile. The suggestion has obvious advantages which have led to several attempts to make such a vehicle; but both experience and engineering considerations have long ago established that the requirements of aircraft and of automobiles are essentially different and their structures although similar in functions are very different in performance. Thus, in fact, the design of a satisfactory automobile is diflicult to reconcile with airplane design.

Among the most troublesome of these difficulties is the design of the power unit. An airplane engine capable of sustaining the vehicle in flight must have characteristics differing in various respects from those which are in an automobile. Thus, if a standard transmission of ordinary design is made heavy enough to transmit the full power of such an engine, it would be too heavy to carry around during flight as an aircraft. Even without regard to the torques transmitted, the clutch, speed-change gearing, differential gearing and rear axle shafts, etc., involve excessive weight for flight and the latter of these, by increasing the unsprung weight, greatly increases the inertial stresses of rough landings.

Aviation engines are designed to operate always with the propeller attached. With the pro successful land-air vehicles.

peller removed, as it must be for. road travel, the engine is easily damaged by "racing and at low speeds its operation is rough. Such engines have been developed by long experience and intensive engineering to meet the requirements of flight with the least possible weight per horse-power. To exchange such engines for a compromise design more nearly meeting the requirements of land travel would necessitate sacrifice of the efficiency now achieved in aircraft.

It is one object of my present invention therefore to provide a power unit for such dual purposes vehicles in which standard aviation type engines can be used and by means of a novel transmission and accessory devices it is made wholly satisfactory for operation of a land vehicle. Another object is to provide such a power unit which is simple, practical, and thoroughly durable. More specific objects are to provide a power unit of the'above character which will be efficient in use, to provide a power unit which can be readily switched from use for an aircraft to use for a land vehicle, to provide a power unit in which the structural units are so disposed and combined as to give adequate strength without heavy construction, and to provide a power unit which is adapted to withstand hard usage as a land vehicle without becoming unsafe for flight. In general it is an object of the invention to overcome difliculties which have stood in the way of Other objects and advantages of the invention will be apparent from the following specification.

In this specification and the accompanying drawings I have set forth one embodiment of my invention and have suggested various modifications and alternatives. It should be understood that these are not intended to be exhaustive or 3 limiting of the invention, but on the contrary are given with a view to enabling others not only to practice my invention, but so fully to understand it and the principles thereof that they will be enabled readily to modify and adapt these examples and to embody the invention in many forms, each as may be best adapted to the conditions of a particular use.

Referring now to the drawings, in which is shown one of the various possible embodiments of this invention,

Figure 1 is a side elevation of the vehicles in which the automobile and airplane sections are connected together,

Figure 2 is a. side elevation, partly broken away, of the automobile and. airplane sections in which the sections have been disconnected and the propeller removed from the automobile section, v

Figure 3 is a diagrammatical showing of the power unit for the vehicle,

Figure 3a is a diagrammatic showing of the ring and pinion gear connection that drives the rear wheels,

Figure 4 is a vertical section taken through the rear portion of the power unit shown in Figure 3, the plane of said section passing through the crankshaft of the motor,

Figure 5 is a vertical section taken on the line 5-5 of Figure 4,

Figure. 6 is a horizontal section taken on the line 6-6 of Figures 4 and 5,

Figure '7 is a rear elevation of the motor taken from the line 'l'| of Figure 4,

Figure 8 is a vertical section taken on a plane perpendicular to Figure 7 and there-below through the hydraulic clutch and the mecha nism associated therewith,

Figure 9 is a horizontal section taken on the line 9-9 of Figure 8,

Figure 10 is a horizontal section taken on the line Ill-40 of Figure 8; and,

Figure 11 is a fragmentary view in elevation of a valve sleeve shown in section in Figure 10.

Similar reference characters refer to similar parts throughout the several views of the drawings.

The power unit described hereinafter is constructed for use in the vehicle described in United States Letters Patent of Robert E. Fulton, Jr., Patent No. 2,430,869 granted November 18, 1947. This vehicle includes an automobile section I which is detachably connected to an airplane section 2. The automobile section is provided with four wheels 3 and 4, a propeller 5, and a motor (Figure 3). The airplane section 2 to which the automobile section is detachably connected as described in the said co-pending application includes a wing I mounted on a fuselage 6 with tail surface generally indicated at 8.

A lever Il (Figure 2) is provided which, when shifted between car and plane positions, conditions the vehicle for operation as an airplane or a car. The propeller 5 may be detached from the motor l0 when it is desired to use the automobile section of the vehicle, e. g., as described in United States Letters Patent of Robert E. Fulton, et al., Patent No. 2,509,096, granted May 23, 1950. In general the power unit includes motor l0 (Figure 3) which, by means of a clutch generally indicated at I I (Figure 4), may be connected to or disconnected from the transmission mechanism which drives one or more of the wheels particularly, as shown, a rear wheel 4 (Figure I) of the automobile section and thus the motor acts as the power unit for the automobile section. The drive to wheel 4 is through a hydraulic clutch generally indicated at l2 (Figure 3), a gear box generally indicated at l3, a drive shaft M, a gear box l5, which includes a reversing gear, shafts l5, l8, and I9, and a pinion I and ring gear 19b in the hub of wheel 4 (Figure 3a).

The crankshaft 20 (Figure 4) ofmotor In is of a standard aviation type engine mounted upon usual bearings not shown, and at its forward end is provided with a thrust bearing toabsorb the thrust of the propeller 5 when the vehicle is used as an airplane. The crankshaft 20 extends rearwardly from the rear main bearing 2! there- 'of to provide a portion 22 on which a cam shaft drive gear 23 and accessory drive gear are ordinarily mounted. As shown in Figure 4, I have replaced the accessory drive gear with a relatively light flywheel 24 to smooth the idling of motor [0 after the propeller has been removed. Although it is desirable, the flywheel is not essential to the operation of the motor as the power unit for the automobile section, if other features of my invention are used as herein described.

A transfer shaft 25 has been added with its left-hand portion as viewed in Figure 4 extending into a bore 26 in the end of crankshaft 20. The left-hand portion of shaft 25 has key slots 28 therein register with key slots in portion 22 of crankshaft 20 and key slots in gear 23 and flywheel 24. Connections between all of these key slots are established by keys 30. Itwill be noted that the portion 22 of crankshaft 20 on which gear 23' and flywheel 24 are mounted is of slightly smaller diameter than the main bearing portion 2|. This forms a shoulder 32 against which gear 23 is held by a nut 35 acting through the hub of flywheel 24. Nut 35 is threaded onto the inner end of crankshaft 20. Because of the length of key slots 28 and because of the depth of 26, crankshaft 20 is free to expand rearwardly, e. g., to accommodate thermal expansion, without affecting the driving connections between the crankshaft 20 and shaft 25.

Shaft 25 has a portion 33 of reduced diameter on which a bevel gear 36 is rotatably mounted. Near the right-hand end 31, shaft 25 is of still further reduced diameter and is splined for engaging a gear 38. The right-hand end of transfer shaft 25 is mounted on a bearing generally indicated at 39 which in turn is held by a clamping ring 4| bolted to housing 40. Shaft 25 is connected to bearing 39 by a cap screw which screws into a threaded bore in the end of shaft 25. Screw 42 acts through the inner ring of bearing 39 to urge the hub of gear 38 toward a seat on shaft 25, which is formed by a wire ring 43 engaging the shoulder between the portion 33 and the right-hand portion 31 of the shaft 25. This ring 43 is not essential to the invention, but is a convenient design for practical manufacture.

The accessory units 44, 45, 46, and 48 (Figures 4 and '7) for motor H! are mounted on, and extend to the right of housing 30 as viewed in Figure 4. These units, which include the magnetos, generator, starter, etc, are driven by gears 48, 49; 50, and 5| which mesh with gear 38 (Figure 7). As gear 38 is driven through splined portion 31 whenever crankshaft 20 turns over, the accessory units except the starter are driven whenever the motor is running.

The jaw clutch H is used to connect the motor to the transmission mechanism. The clutch engages dogs on both gear 38 and gear 36. whenever it is desired to operate the automobile section of the vehicle. The clutch ring 52 of clutch ll (Figures 4, 5, and 6) has a plurality of teeth 53 which engage between teeth 54 and ride on the hub of bevel gear 36. To provide for movement of clutch ring 52 into engaged or disengaged position a grooved clevis 56 is fitted over the periphery of ring 52. This clevis has a pair of pins 51 extending outwardly therefrom and diametrically positioned thereon with respect to ring 52. A yoke generally indicated at 60 is pivotally mounted by a pin 6! (Figure 6) on a bracket 62 on housing 40. The ends of the two arms of this yoke are slotted to receive pins 51 and thus, as yoke 60 is pivoted upon its pivot pin 6|, it acts through clevis 56 to move clutch ring 52 into and out of engagement with teeth 63 integral with and extending forwardly from gear 38. A link 64, which extends through a gland member 65 on the housing 40, is pivoted at 66 to yoke 60.

As described in United States Letters Patent 01' Robert E. Fulton, Jr., et al., Patent No. 2,509,095, granted May 23, 1950, two ignition locks for the land vehicle and airplane operation respectively, and a master lever I'I interlocking therewith control the shifting from one type of operation to the other. Since the yoke 60 is connected to and controlled by the master lever I! (Figure 2) and the masterlever can only be moved when the ignition locks are both off, clutch ll cannot be moved into engaged position with respect to the teeth on gear 38 when gear 38 is being driven.

As described in the above patent, cable 34 is moved whenever the master lever I1 is shifted. Referring to Figure 3, this cable 34 is connected to onearm of a bell crank 61 pivotally mounted at 68 on the framework of the automobile section. The other end of this bell crank is pivotally connected to the clutch shifter link 64. The clutch shifter link 64 is thus moved inwardly or outwardly depending upon the direction in which the master lever is moved. Referring again to Figure 6, it can be seen that, when cable 34 moves rod 64 inwardly from the position it occupies in Figure 6, it shifts the jaw clutch ring 52 into engaged relationship with teeth 63 and when rod 64 is moved outwardly, the jaw clutch ring 52 is high transmission speed is carried right thru to the driving wheel, where it is geared down to wheel speed by a small pinion driving an internal ring gear (not shown) in the hub I62, and even at this point the wheels are made smaller than in a normal automobile to keep down the weight of the gearing. This stepped-up transmission becomes feasible for low-cost production because its operation is limited to the relatively lower speed of automobile operation bythe governor I60, and the clutch l I, both interlocked with the shift-over device ll so that the motor cannot be run at full speed when the transmission is connected; and the transmission is disconnected when the engine is set to run at full speed (as in take-off).

The shaft 13 is mounted on bearing 14 which in turn is mounted on housing 40 between a universal joint housing 15 and a locking snap ring 16. The inner race of bearing I4 is clamped between a nut 'I'I threaded on shaft 13 and the hub moved to a disengaged position. Because the I clutch I I can never be moved unless the motor l0 has been stopped, it is quite likely that its teeth 53 may not register with the spaces between teeth 63 on gear 36, and consequently. that the ring 56 cannot move to its engaged position when lever I! is shifted. This is taken care of by the spring connection 69 in the link 64. If the teeth of jaw clutch ll are not in register, yoke 60 can move only a short distance, but since the movement of the master lever l1 pushes in the link 64, its full distance, the remainder of the movement is absorbed by movement of push rod 64 into the cup 10, compressing spring 69 between them. As soon as the motor begins to turn, so that the teeth of clutch ll come into register, spring 69 acting on cup 10' pushes the yoke 60 back and thus snaps the ring 56 into its engaging position.

Referring to Figure 4, bevel gear 36 engages and drives a bevel pinion gear 12 keyed to the tapered end of a shaft I3. In the example shown, the ratio between gears 36 and 12 is one to five.

Such a step-up in transmission speed is very imof gear 12, gear 12 in turn being held by a nut 18.

Universal joint housing 15 is mounted on housing 40 by nuts 18 on stud bolts in the housing 40; and to prevent oil from leaking along shaft 13 out of housing 40 a needle bearing is provided.

A universal joint (generally indicated at as a type having constant angular velocity, available under the name Tracto from the New Process Gear Company) positioned without housing I5 connects the lower end of shaft 13 to a shaft 8|. Shaft 8| has positioned thereon by bearings '82, a sleeve member 83, which constitutes the lower half of a ball and socket housing for the universal joint 80. The bell-shaped upper end of this sleeve 83 is resiliently held in engagement with the lower end of universal joint housing 15 by a spring 84, thus forming a greasetight gland. A second gland 85 is provided at the lower end of sleeve 83 is held against the shaft by garter spring 86. A snap ring 81 holds this gland positioned in the sleeve and an inner snapring holds the bearings 82.

Shaft 8| extends downwardly from universal joint 80 as shown in Figure 8, and drives a fan 88, advantageously a narrow bladed high-speed propeller fan. Thus, whenever the motor is running with the master lever I! set for land operation, the fan 88 operates to draw air through a housing, diagrammatically indicated at 89 (Figure 3), over cooling surfaces of the motor l0 and hydraulic clutch l2 which is positioned immediately beneath the fan. In the example illustrated, the motor is cooled directly through fins on its cylinders and their heads; but obviously, its heat may be transferred to cooling surfaces by a liquid coolant, and this is in fact done in the clutch, wherein the oil is pumped in continuous circuit through a cooling member. Instead of connecting the fan through the disconnect clutch II, it may be'connected to the motor through a centrifugal clutch which disconnects its drive at a predetermined maximum speed at or above the highest speed attainable when the controls are set for automobile operation, and re-connects only when the speed drops below said maximum. When the combination operates as an airplane, its driving propeller will, of course, create a sufficient air flow for cooling without operation of the fan 88. r

The impeller portion 90 (Figures 8 and 9) of hydraulic clutch I2 is driven through a splined fiange member 9| which fits complementary splines formed on the drive shaft 92, which, in effect, is an extension of shaft 8 I. This, as well as a splined connection between shafts 8| and 92, permits vertical movement of motor I with respect to clutch I2 which is secured on the automobile frame.

Flanged member 9I is connected by bolts 93 to the radially vaned semi-toroidal impeller member 94 which, together with impeller housing members 95, 90, 91, and 9B rotate with shaft 92. The driven portion of the clutch consists of the radially vaned semi-toroidal-rotor 99 (members 85 and 99 are generally called the grapefruits) and the central frame member I00, which is bolted to the flanged ring IN on the driven shaft I02 and is brazed or welded to the grapefruit 99. Each of these grapefruits 94 and 99 is provided with angularly spaced radial vanes I03, I04, and a semi-toroidal core I05, I06, to form a throat near the periphery-all in accord with standard practice in such turbo-type fluid couplings.

The driving portion 90 of hydraulic clutch I2 is rotatably mounted upon the driven shaft I02 by a pair of bearings I07 and I08, and the driven member, as indicated above, is secured on shaft I02 in driving relation thereto by bolting the central frame member I00 to the flanged sleeve member IOI welded or brazed onto shaft I02. The upper end of this sleeve IOI also forms a seat on which bearing I0'I is-held by nut I09. Bearing I00 is mounted on ring member 98 between a flange II 0 and a lock ring III. These bearings permit the driving portion 90 of the clutch to rotate freely with respect to shaft I02, and thus shaft I02, which is turned by the driven portion of clutch I2, is also freely rotatable with respect to the driving portion of the clutch. Thus the only connection between the driving and driven portions of the clutch is through the hydraulic fluid introduced into the clutch as described hereinafter.

When portion 90 of the clutch is driven and hydraulic fluid is introduced therein through holes H2 in the hollow shaft I02 and sleeve IOI, centrifugal force due to the spinning of member 90 throws the fluid outwardly in the hydraulic clutch. If the radial depth of fluid is suiiicient, it forms a transfer medium transferring power from the driving portion of the clutch to the driven member 99 and thus to tubular shaft I02.

To supply oil to clutch I2, an impeller type pump H3 is provided at the bottom of shaft 92 (Figure 8). Pump I I3 is driven by shaft 92 whenever the motor is running and the master lever I1 is set forland operations. From this pump oil is forced upwardly through space between shafts 92 and I02 and thence into the clutch through a plurality of ports II2. This pump is designed to provide at all times an excess of oil beyond the requirement of the clutch and the excess is drained back through a pair of diametrically disposed valves I I4.

Each valve H4 is mounted, as shown in Figure 8, upon the bottom of the driven portion 90 by a pipe I2I and braced by a bracket II5 hidden in Figure 8, but shown in section on Figure 10. The valve II4 includes a body 0 (Figure 10) cylindrically shaped in cross-section having a. slot III (Figures 8 and 11) cut through its sidewall, this slot being spiral from end to end and then brought back longitudinally at III'. An inner sleeve H9 is rotatably fitted into body III; and provided with ports I adapted to register with a pipe I2I in all positions of sleeve I I9, and provided also with a longitudinal slot I20 which crosses the slot III. The point at which these slots cross or register depends, of course, upon the rotational position of sleeve H9.

The valve H4 is connected by a pipe I 2I to a hole I22 extending through portion 96 of the clutch adjacent the periphery thereof. Excess hydraulic fluid from the interior of housing 96 drains through hole I22, tube I2I, body H6, and ports I20 to the interior of sleeve H9, and then along the longitudinal slot I20 until it reaches a registering hole or portion of slot 1; whereupon it escapes into housing I23 eventually to drain back through pipe I24 into a sump I25 thence to be pumped again to the clutch.

Sleeve H9 is closed at its inner end and provided with a bearing plate I2I at its outer end. A ball bearing I26 is positioned between its outer end plate I21 and the outer end I28 of valve body IIG to assure coaxial alignment and permit sleeve II9 to be easily turned when the valve is rotating at a high rate of speed with the driving portion of the clutch.

The inner end of sleeve H9 is mounted in a needle bearing I26 and then projects beyond the body II6 where it is provided with a gear I29 by which it is rotated to bring the opening through the registering portions of slots I20 and Ill closer tovor farther from the pipe I2I. this opening forms the overflow outlet from the rotating annulus of oil in the portion 90 of the clutch, such rotary adjustment of sleeve I I9 controls the radial level of the oil in said annulus, and accordingly the valve II4 permits the user to control the amount of power transmitted by the clutch.

To turn gear I29 (Figure 10) and thus change the setting of valve II4, a ring-shaped member I30, best shown in, (Figure 8) having helical threads thereon is mounted on complementary threads on the housing of gear box I3. Ring shaped member I30 carries a bearing I3I on its upper portion and the outer race of bearing i3I has a cylindrically shaped rack I32 (i. e. having annular flanges of gear tooth section) secured thereto. As ring member I30 is raised and lowered, the teeth on rack I32 act upon gear I29 to rotate, and thus adjust. sleeve I I9 in valve H4. An arm I33 on ring I30 is connected by suitable linkage (omitted in Figure 8 to avoid confusion of lines and shown diagrammatically as hell crank I34 and Bowden wire I35 in Figure 3) connected to the accelerator pedal I36 or an operative part I31 connected thereto. Thus, whenever the accelerator pedal is pressed inwardly, ring I30 is rotated with respect to gear box I3 causing ring I32 to move upwardly and thus adjust valve II4 to increase the radial depth of the fluid in the clutch; and whenever the pedal is released, valve H4 reduces the radial depth of the fluid in the clutch.

The housing I23 already mentioned. encloses both the hydraulic clutch and the valve adjusting mechanism just described. This housing is clamped onto a neck of housing I30 for gear box I3 as shown in Figure 8, and is provided with gasket I39 to protect against oil leakage.

At its lower end shaft I02 is mounted on a bearing I40 (Figure 8) which in turn is mounted on a housing member I4I secured to the housing I38 of gear box I3. A pilot shaft I43 extends upwardly into the lower portion of shaft I02 and its lower end is mounted in bearing I44. A sleeve I45 on the exterior of shaft I43 serves as a spacer to position bevel pinion I46 with respect to bearings I40 and I44 and engage a 1| castellated hub on gear I46 with the end of shaft Since I I02. Thus the shaft I02 can be readily withdrawn from the gear box I3 and the latter is removable as a unit without removing the clutch.

Bevel gear I46 drives a longitudinal drive shaft I4 through a bevel gear I50 thereon. The end of shaft I4 is mounted in the gear box I3 by a bearing I52. The ratio between the gears I46 and I50 as shown is three to two, thus reducing somewhat its operating speed as compared with the clutch, which benefits most from the increased speed, but still retaining asubstantial mechanical advantage with respect to both the motor and the road wheel.

Referring to Figure 3, shaft I4 acts through a reversing gear box I5 controlled by a manually operable lever I5I to drive wheel 4 either forward or back. The gear box I5 operates with a 1:1

ratio, as shown. The connection between wheel 4 and the gear box I5 is through shafts I6, I8 and I9, universal joints I58 and I59 which permit the wheel to move freely with respect to the body of the vehicle when it is being used as a portion of the landing gear 'fof the airplane when driving over bumps when 'used as an automobile, a pinion (not shown) on the end of shaft I9 at 4,'and ring gear (not shown) on the hub wheel 4. The pinion and ring gear ratio is such as is necessary to reduce wheel R. P. M. back down from high drive-shaft speed (permitting light weight mechanism) to proper wheel R. P. M. for driving.

The governor I60 (Figure 3) may be any standard type (e. g. a spring-loaded fly ball governor) adjustable to maintain any speed within a predetermined range. It is connected to the carburetor I6I of the motor so as to control the throttle adjustment, and manual controls adjust the speed setting of the governor rather than the throttle as is usual. As the load upon the motor is increased by adjusting valve II4 to increase the radial depth of hydraulic fluid in the hydraulic clutch, the governor I60 maintains the minimum satisfactory speed of the motor, e. g., approximately 600 R. P. M. When the valve is adjusted to maximum depth so that the hydraulic clutch is operating at maximum efficiency, then the speed of the motor may be increased by adjusting governor I69, e. g., up to 1200 R. P. M. These latter changes are transmitted through the clutch to the wheel 4 with corresponding increases in the speed of the vehicle. When valve I05 is adjusted to empty liquid from the clutch, it is, of course, effectively disengaged and the motor runs idle.

Thus, by a simple accelerator pedal the operator of the vehicle controls its speed when used as an automobile first by varying the radial depth of the liquid in the hydraulic clutch and subsequently by adjusting the governor. It will be understood, however, that this interrelated, single pedal control is not essential to other features of the invention. The governor may with advantage also be coordinated also with another element whose position or condition indicates the loading of the motor, so as to allow the motor under heavy load to come up to a higher speed than is permitted in normal operation, e. g., to maximum torque.

Even with the transmission features set forth above, it is found advantageous to use a drive ratio between motor and wheels such that the maximum load during operation as an automobile occurs at motor speeds substantially lower than the speed of maximum loading during operation as an aircraft. This is another respect in which the requirements of aircraft and automobile engines are inconsistent and would normally result in unsatisfactory performance of the engines for automobile use. According to the present invention, however, this difliculty is avoided by shifting the range of spark timing when the change over is made from aircraft to automobile operation and vice versa. As shown, this is accomplished by rotating the housing and-with it the field magnets distributor points, etc. of the magnetos 45, 41, about their rotors. As shown (in Figure 7), these magneto housings are mounted on the housing 40 by bolts in arcuate slots while a cylindrical flange on the magneto housing fits into a corresponding cylindrical opening in the housing 40. When the master control lever I1 is thrown from one position to the other it acts thru suitable connecting linkage (shown diagrammatically at I in Figure 3) to rotate the housings of magnetos 45 and 41 thru the angle adapted to bring the spark timing range to the proper angular position. As shown (in Figure 7) this linkage terminates in a toggle I66 having its ends, respectively connected to arms I68 pivoted on the magneto housings respectively and on a central slide I69 movable axially in bearings I10 parallel to the axis of the magnetos, whereby the toggle action is distributed equally to the two magnetos. The particular shift will depend upon the characteristics of the motor used and the other features of design of the auto and airplane.

In the example illustrated a shift of 15 is made in thespark retard direction for auto operation and in the advance direction for aircraft operation. Instead of rotating the magneto housing, one may also use a type of magnetos e. g., such as that used on certain flying boats, with a built in spark-retarding mechanism provided that the mechanism is capable of sufficiently shifting the range of operation while still allowing adjustment, manual or automatic, of

spark timing within that range to meet varying conditions of operation.

By use of a cushioning type coupling I2 in the transmission mechanism, I have first of all protected the aviation motor from road shocks and overloads which it is not designed to withstand. By permitting any desired degree of slip and providing for efficient cooling and recirculation of the fluid used in the coupling, and thus making possible the utilization of any part of the available engine torque up to its maximum, I have avoided the necessity for a change-speed transmission device and thus eliminated a major source of excess weight. By gearing the transmission up to a relatively high ratio above the engine speed, I have greatly increased the efliciency of the centrifugal inertia type coupling to the point where I am able to use, for example, couplings substantially the same as those used on aircraft for driving superchargers, and thus excess weight for the land operation is further reduced. By means of the radial level control in the hydraulic coupling, I am able to give the operator, during land operation at speeds below the equivalent of the minimum engine speed, full control substantially equal in all respects to the accelerator control of an ordinary automobile, and I have avoided to apply the full power of the engine for hill climbing etc., while protecting the engine from tearing itself to pieces in idle racing, as an aircraft engine will if relieved of its propeller load.

By use of an additional mechanical clutch between the motor shaft and the transmission mechanism, I have made possible the high gear ratio without the necessity for designing it to withstand the tremendous speeds which would be involved if the high gear ratio were effective during aircraft operation. By connecting this additional clutch and the service clutch, I assure the necessary volume of cooling air for land operation, but again I avoid the excessive speeds which would be likely to damage the fan if it were connected during operation as an aircraft.

By use of the air duct with forced circulation, I am able to operate on land like an air-cooled automobile and in addition to provide efficient cooling for the slipping clutch; and by using a narrow blade propeller, or other circulating means offering little or no obstruction in the duct when idle (as in flight) and providing a smooth flow path from the front of the engine to a point on the fuselage where the cooling air can be discharged without loss of aerodynamic efliciency of the aircraft, I have overcome the objection that aircraft engines seriously overheat when deprived of the strong air blast provided by their own propellers.

By gearing up the transmission to a speed above that of the motor, I have greatly reduced the weight of all parts of .the transmission mechanism, and by carrying this high-speed drive, not merely to the rear axle, but right into.

the wheel, and even using relatively small wheels, I have eliminated such heavy parts as differential gearing and driving axles which are commonly found on automobiles. This is of especial importance in the dual purpose vehicle described above,

because such parts, being unsprung weight, would if present require excessively heavy framing and housings etc., to withstand the inertial stresses imposed by a rough landing or take-off.

The drive to a single wheel, as shown, although not essential to the invention, is advantageous in eliminating the drive shaft and gearing to other wheels, and has proven adequate because of the effectiveness of the other features of the invention in reducing the weight of the vehicle. It will be understood, also the drive may be to any one or more of the vehicle wheels.

Accordingly, a thoroughly eiflcient and practical mechanism has been described in which the power unit of an airplane is utilised as the power unit for a car comprisinga section of the airplane. Furthermore, by the use of this mechanism the weight of the airplane is kept at a minimum without sacrificing efliciency in operation. It will thus be seen-that the several objects hereinabove mentioned have been successfully accomplished.

Although the various features described above all cooperate in the total result described and interact with one another to give cumulative advantages, it will have been evident from the foregoing that many of them individually have such outstanding advantages that they will be 12 found desirable even where the other features, for some reason, are not desired.

What is claimed is:

1. Power transmission and control mechanism for transmitting power between the power plant and at least one wheel of a combined air and land vehicle having a single power plant, that comprises a positive, locking-type clutch connected to receive power from the power plant, a step-up gearing connected to receive power from the clutch, a centrifugal fluid coupling connected to receive power from the step-up gearing, a reverse gearing connected to receive power from the centrifugal fluid coupling and a step-down gearing connected to receive power from the reverse gearing and transmit power to a wheel of the vehicle.

2. Power transmission and control mechanism as defined in claim 1, further characterized in that it includes means for controlling the coupling of the centrifugal fluid coupling, means for controlling the power generated by the power plant and a common means for simultaneously operating both of said control means.

3. Power transmission and control mechanism as defined in claim 1, further characterized in that it includes a valve for controlling the amount of fluid in the centrifugal fluid coupling, a throttle valve for the power plant and an accelerator cou- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,923,225 Moorhouse Aug. 22, 1933 1,934,385 Strauss Nov. 7, 1933 1,963,720 Sinclair June 19, 1934 1,975,505 Fottinger Oct. 2, 1934 2,115,125 Sinclair Apr. 26, 1938 2,135,073 Gerhardt et al Nov. 1, 1938 2,174,946 Ray et a1. Oct. 3, 1939 2,202,455 Klavik May 28, 1940 2,215,003 Johnson Sept. 17, 1940 2,255,773 Heftler Sept. 16, 1941 2,289,440 Kugel July 14, 1942 2,296,642 Huebner Sept. 22, 1942 2,301,957 Lang Nov. 17, 1942 2,318,187 Addison May 4, 1943 2,373,467 Frakes Apr. 10, 1945 2,376,699 Jandasek May 22, 1945 2,427,936 Walls Sept. 23, 1947 2,444,691 Barnes July 6, 1948 FOREIGN PATENTS Number Country Date 472,619 Great Britain Dec. 21, 1935 

